Industrial liquid fuel atomizers, or nozzles, often employ steam to effect the atomization of the fuel as it is injected into furnaces, boilers and the like. Typically, such nozzles employ energy from the steam to transform the liquid fuel into minute, suspended droplets, or to atomize the fuel, so as to assure an efficient combustion and minimize the discharge of pollutants.
The fuel atomizing steam must, of course, be separately generated and requires an amount of energy that is directly proportional to the amount of steam that is consumed by the nozzle. In the past, efficient nozzles consumed steam at a rate of about 0.1 to 0.4 lbs. of steam per pound of fuel oil atomized by the nozzle and discharged into the furnace. The generation of this steam heretofore added as much as 2.8% to the fuel consumed by the furnace. Fuel expended for generating atomizing steam is essentially lost as an energy source for the furnace and, in the overall energy balance of the furnace constitutes wasted energy. Consequently, in view of rapidly escalating energy costs, it is highly important to minimize the consumption of fuel atomizing steam and thereby reduce energy waste.
Although a certain amount of energy (supplied by the steam) is necessary to apply the required shear forces to the liquid fuel so as to transform it into small droplets, a large if not a major portion of the energy carried by the atomizing steam is simply dissipated in the nozzle due to the intricate shape of passages through which the steam must travel, which is an inefficient use of the steam, so that much of it is discharged from the nozzle without really contributing to the atomization of fuel, etc.
An additional problem encountered with many atomizing nozzles, which during operation are subjected to high temperature from the surrounding combustion chamber of the furnace, is a fouling of the nozzles, or at least portions thereof due to the deposition of fuel particles on (hot) nozzle surfaces contacted by the fuel, a coking of such particles and the like. This requires a frequent cleaning of the nozzle, with a corresponding downtime for the burner and further contributes to the discharge of pollutants due to the formation of incompletely combusted fuel particles, the formation of soot and the like which is discharged as part of the exhaust to the atmosphere and/or which can foul surfaces of the furnace or the exhaust stack. Accordingly, there is presently a need for a liquid fuel atomizing nozzle which overcomes the heretofore encountered shortcomings in general and which specifically reduces the energy consumption of such nozzles.